Tandem Helicopter using 2x Mini-Titan

[Super-Hornet]

Giving up on dualcopter using propeller on my previous project...so salvage everything and added a few more things to build this Tandem Helicopter.

Not yet tested flying yet because still tuning the electronics.

The parts are:
2x spare parts of Mini-Titan.
1x Mini-Titan torque tube.
1x Scorpion MKII-2221-10 motor
1x Castle Creations Phoenix 45A
1x Aurora 9's RX
1x KKv2.0 Board.
6x Hitec HS-65 servos
2x Taroq Flybarless head. Can't find 3 bladed head so get 2 bladed one instead.
2x Pairs of 360mm Blades.

Using 3S1P 3000mAH battery.

Blades/Servos controlling and stabilization is done using KKv2.0 board. Trick is connecting Pitch (CH6) channel to the throttle channel of the KKv2.0 board.

Will update when have the chance to test flight.

[nb8686]

Very cool project. Thanks for sharing.

[feudallordcult]

any chance of blade strike?

[Super-Hornet]

Thanks..

Nope... the blades will not strike each other because it is in sync on each other. Motor drive the rear rotor and the rear rotor drive the front rotor.

The only time the blade will strike each other is when the tail drive shaft fail.

[Ben]

1) both rotors on Fixed Pitch?
2) kk board able to support 2 Rotors?

Best wishes to your "Chinnock" project and safe landing. Trust Rotors synchro by same driving belt (high risk if belt break as blades may strike one another)

[Super-Hornet]

My first tandem project was using trex450 a few years back... and it was using belt driven. The problem of using belt is that... during loading, when the belt slip gear, the rotor will be out of sync...and thus, blades strike. During that time, torque tube not exists in 450 size yet.

Now, i am using torque tube...so it is better. Only if when the gears breaks or torque tube failure.. then both rotor will be out of sync.

Both rotor are in collective pitch. I configure the kkv2.0 board in 1 motor 4 servo mode. It does not matter what mode anyway because i need to change all channel's mixing. So i use channel 2 to 7. Channel 2,3,4 goes to frontal servos. Channel 4,5,6 goes to rear servos. Channel 8 connect to a BEC to drives all 6 servos.

I configure the mixing so it follow the real "Chinook" controlling... which mean:
Take off.. all 6 servos move to change both rotor to increase pitch.
Elevator...frontal 3 servos reduces the pitch while the rear 3servos increases the pitch.
Yaw/Rudder...frontal 2 servo move to tilt swash plate just like normal 120Degree swash plate in single rotor heli's aileron. Rear two servos move to tilt the rear swash plate in opposide direction to frontal one.
Aileron... only the frontal 2servos move to tilt frontal swash plate.

By doing so.. i hope it can follow the real Chinnook way of turning on center axis, front axis or rear axis.

[Aramid]

Great stuff, bro. Keep us updated!

[nese]

Nice project. Initially I was thinking about how the counter-rotating rotors of a Chinook worked for the normal cyclic movements... Thinking of the mixing gave me a headache. Looking forward to seeing it take off and fly.

Btw, why did you give up the dual-copter? Do you think a dual copter platform is too unstable?

I was looking at Walkera's offering on youtube and thought after seeing Alishanmao crash it that it didn't look too fun to fly. lol

[Super-Hornet]

The reason i gave up on dualcopter using propeller is that, by tilting the propellers for elevator stabilty will not provide any stability (or very too little). IMHO, it should be tilting the rotor blades instead of turning the motor for stability. That mean.. it should be variable pitch like in helicopter rotor instead of propeller. On motor with propeller, by tilting the propeller do not provide the "breaking effect".. thus the craft will not stop immediately when u pull up the elevator stick.

BTW.. Not sure whether the website i read is wrongly interpret or i interpret wrongly regarding for aileron, only frontal swash is titled. I find that this way of controlling is a bit strange.

So, instead of tilting frontal swash only, I update/change my tandem heli controlling for aileron whereby both frontal and rear swash plate tilt in unison when applying aileron.

This should give a better/nature controlling like in single rotor heli. It should provide more side movement stability as well. By applying aileron and rudder stick movement, turning on center, frontal and rear axis can be achieved.

[Adrianli]

See thread title and knew it, must be u lah.

This weekend got test flight?

[Rajie]

Awesome project! I still have the impression that the blades will strike, even if you say they won't.

[Super-Hornet]

If this weekend good weather, then can test fly it.

As for the blade strike...then Chinook and Sea Knight will suffers from blade strikes as well.
Just hope that the torque tube do not fail on me.

Ching Hock

[Ben]

Awesome project! I still have the impression that the blades will strike, even if you say they won't.

It is a mechanical gear linkages. Trust Super Hornet has done gear ratio due diligent. If ratio is incorrect, then blades will hit after some cycle.

[nese]

IMHO for dualcopters the elevator movement to control the thrust vector would have a similar overall effect between the direction of props vs swashplate. I expect the main difference to be that the collective method would probably be faster in correction and balancing. If not some other combination of motor and prop could optimize the reaction time. So I was guessing getting that stability was challenging.

For the aileron movement of a Chinook style flight I'm thinking it would make sense in fwd flight that only the front swash would move while the back swash remains as it was to allow the 'tail' to trail behind for some stability, but I guess for hovering it doesn't seem to make sense as applying aileron to tilt just the front swash may translate to a yaw movement. Then again, the physics of this is interesting... test flight video please

The reason i gave up on dualcopter using propeller is that, by tilting the propellers for elevator stabilty will not provide any stability (or very too little). IMHO, it should be tilting the rotor blades instead of turning the motor for stability. That mean.. it should be variable pitch like in helicopter rotor instead of propeller. On motor with propeller, by tilting the propeller do not provide the "breaking effect".. thus the craft will not stop immediately when u pull up the elevator stick.

BTW.. Not sure whether the website i read is wrongly interpret or i interpret wrongly regarding for aileron, only frontal swash is titled. I find that this way of controlling is a bit strange.

So, instead of tilting frontal swash only, I update/change my tandem heli controlling for aileron whereby both frontal and rear swash plate tilt in unison when applying aileron.

This should give a better/nature controlling like in single rotor heli. It should provide more side movement stability as well. By applying aileron and rudder stick movement, turning on center, frontal and rear axis can be achieved.

[Super-Hornet]

Hi All

Here is the new updates. Maiden flight on this morning.
Enjoy the video (or complain if u want to):
{ Link in case the embedded not working: http://www.youtube.com/watch?v=KvCwCAAzhv8 }

Some shaking during forward flight...probably due to either one or more possible reason:
1. Servos has insufficient current due to "ribbon" cable not thick enough.
2. Rotor head has some parts loose... CANNOT trust Tarot parts.
3. Servo HS-65 not high torque enough?

Will dismantle the Tarot heads and do a complete disassemble and reassemble to fix any "loose" rotor head that might cause heli to shake during forward flight.
Will also increase the power supply to the servos as well.

Note:
Thanks to "Adrianli" for being the Video Cameraman and "ang" for the Control Tower controller